The activity of vacuolar H+-ATPase (V-ATPase) in the apical membrane of blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT). 5-HT induces, via protein kinase A, the phosphorylation of V-ATPase subunit C and the assembly of V-ATPase holoenzymes. The protein phosphatase responsible for the dephosphorylation of subunit C and V-ATPase inactivation is not as yet known. We show here that inhibitors of protein phosphatases PP1 and PP2A (tautomycin, ocadaic acid) and PP2B (cyclosporin A, FK-506) do not prevent V-ATPase deactivation and dephosphorylation of subunit C. A decrease in the intracellular Mg2+ level caused by loading secretory cells with EDTA-AM leads to the activation of proton pumping in the absence of 5-HT, prolongs the 5-HT-induced response in proton pumping, and inhibits the dephosphorylation of subunit C. Thus, the deactivation of V-ATPase is most probably mediated by a protein phosphatase that is insensitive to okadaic acid and that requires Mg2+, namely, a member of the PP2C protein family. By molecular biological techniques, we demonstrate the expression of at least two PP2C protein family members in blowfly salivary glands. © 2009 Wiley Periodicals, Inc.
| Identifer | oai:union.ndltd.org:Potsdam/oai:kobv.de-opus-ubp:4436 |
| Date | January 2009 |
| Creators | Voss, Martin, Blenau, Wolfgang, Walz, Bernd, Baumann, Otto |
| Publisher | Universität Potsdam, Mathematisch-Naturwissenschaftliche Fakultät. Institut für Biochemie und Biologie |
| Source Sets | Potsdam University |
| Language | English |
| Detected Language | English |
| Type | Postprint |
| Format | application/pdf |
| Source | Archives of insect biochemistry and physiology 71 (2009), 3, S. 130 - 138, DOI 10.1002/arch.20310 |
| Rights | http://opus.kobv.de/ubp/doku/urheberrecht.php, Volltextzugriff: Universitätsverlag - eingeschränkter Zugriff |
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